ASME B16.1:2020 pdf free download – Gray Iron Pipe Flanges and Flanged Fittings
3.1 General
Pressure-temperature ratings are maximum allowableworking pressures in bar (psi) units at the temperature indegrees Celsius (Fahrenheit] shown in Table 3.1-1 for theapplicable material and class designation. For inter-mediate temperatures, linear interpolation is permitted.lnterpolation between class designations is not permitted.
3.2 Flanged Joints
A flanged joint is composed of independent interrelatedcomponents: the flanges,gasket,and bolting, which areassembled manually. Proper controls must be exercisedin the selection and application for these elements toattain a joint that has acceptable leak tightness. Specialtechniques,such as controlled bolt tightening describedin ASME PCC-1, may be used to achieve a tight joint inservice.
3.3 Rating Temperature
Temperatures shown for the corresponding pressurerating shall be the material temperature of the pres-sure-retaining structure.It may be assumed that the mate-rial temperature is the same as the fluid temperature. Useof a pressure rating at a material temperature other thanthat of the contained fluid is the responsibility of the userand subject to the requirements of any applicable code orregulation.
3.4 Low-Temperature Ratings
Pressure ratings for temperatures below -29°℃ (-20F)should be determined in accordance with low-tempera-ture properties of gray iron (ASTM A126) as governed byapplicable code or regulation.
3.5 Ductility
Gray iron has little ductility ; therefore, the resistance ofthese flanges and flanged fittings to excessive forces andsuddenly applied loads is significantly less than for moreductile materials, such as steel.The following precautionsare recommended:
(a) These flanges and flanged fittings should not beused where suddenly applied loads such as rapid pressurefluctuation may occur.
(b) Alignment of flange faces is essential along withcontrol of assembly bolt torque so as not to over-stress the gray iron flanges.Care should also be exercisedtoensure that pipingloads transmitted to gray iron flangesare controlled.
5.2 Flanges
The manufacturer’s name or trademark shall be cast onall loose flanges.In addition, the numeral 25 shall be caston Class 25 flanges. Numerals for other classes designa-tions shall be cast on loose flanges in addition to the re-quirements of para.5.3.
5.3 Material Class
ln those sizes and pressure-rating class designations,where ASTM A126, both Classes A and B iron, can beused, see para.6.1,letter A or B shall be cast on bothflanges and fittings in the proximity of the numerals.Flanges and fittings with no A or B Class iron markingshall be considered as Class A iron for rating purposes.
7.3.3 Tees,Crosses, and Laterals
(a) Thecenter-to-face dimensions for straight-size teesand crosses, with or without side outlet, and laterals areshown in Tables 7.3.2-1 through 7.3.2-3.
(b) Reducing tees and reducing crosses, with orwithout side outlet, and reducing laterals. NPS 16 andsmaller, shall have the same center-to-face dimensionsas straight-size fittings shown in Tables 7.3.2-1through 7.3.2-3 corresponding to the size of the largestopening.For NPS 18 and larger, if the outlet of a reducingtee; the branch ofa reducing lateral; or the largest outlet ofa reducing side outlet tee, reducing cross,and reducingside outlet cross is the same size or smaller than givenin Tables 7.3.2-1 through 7.3.2-3 (short-body pattern),the center-to-face dimensions shown in these Tablesshall be used. If a branch or any outlet is larger thanshown in Tables 7.3.2-1 through 7.3.2-3, the center-to-face dimensions shall be the same as for the straight-size fitting shown in Tables 7.3.2-1 through 7.3.2-3 corre-sponding to the size of the largest opening.Tees, crosses,and laterals, reducing on the run only,shall have the samecenter-to-face dimensions as straight-size fittings shownin Tables 7.3.2-1 through 7.3.2-3 corresponding to the sizeof the largest opening.
(c) Tees reducing on both runs are generally known asbull-head tees and have the same center-to-face dimen-sions as straight-size fittings corresponding to the size ofthe outlet.